Automated assembly equipment, including robotic assembly equipment, commonly picks and places assembly components using some form of end effector coupled to a movable supporting structure such as a robotic arm. When picking and placing the assembly component using a vacuum nozzle as an end effector, typically a conventional vacuum sensor detects a change in air pressure at the vacuum nozzle that indicates the presence of the assembly component. The assembly component is then placed at the desired location. For example, an integrated circuit component (an IC) is placed on a circuit supporting substrate, e.g., a printed circuit board, in a manufacturing process for assembly in an electronic device. The vacuum nozzle end effector typically applies a predetermined force to the IC component in the direction of the placing operation against the circuit supporting substrate to properly set the IC component on the circuit supporting substrate.
In the case of surface mount IC components, the force pressing the component to the surface of the circuit supporting substrate is necessary to effect contact between each of a plurality of pads and a plurality of pre-soldered contacts, respectively. The plurality of pads and the corresponding plurality of pre-soldered contacts are normally located on opposing surfaces between the IC component and the circuit supporting substrate. Either of the two opposing surfaces can comprise the pads and the other surface the pre-soldered contacts such that when the IC component is placed on the predetermined location on the surface of the circuit supporting substrate the presoldered contacts and the pads are mechanically contacting each other, respectively.
Regrettably, after a placement operation, the assembly component, such as a surface mount IC component, may not be electrically connected to a circuit on the circuit supporting substrate due to improper placement force being applied to the component upon being placed on the circuit supporting substrate. For example, a plurality of pads and pre-soldered contacts require a certain amount of force pressing the two opposing surfaces together to allow all the pre-soldered contacts to settle against the respective pads to effect mechanical and electrical contact therebetween, respectively. This condition can be a significant cause of assembly and manufacturing failures, which is unfortunately detected well after all components are assembled on the circuit supporting substrate. The testing, diagnosing, and repair costs can be significant. Also, the quality of the manufactured product can be severely affected as perceived by the consumer.
Additionally, the end effector is usually required to pick and place different types of assembly components on the circuit supporting substrate during an assembly process. These different assembly components may require different amounts of placing force to be properly placed on the circuit supporting substrate. For example, different surface mount ICs placed on a circuit board will have different numbers of pads assembled to respective presoldered contacts between the ICs and the circuit board. That is, the number of contacts between the different IC components ant the surface of the circuit supporting substrate can vary from placement of a first IC to placement of a second IC. The varying number of contacts between placement operations may require different amounts of placement force to effectively place the different IC components on the circuit supporting substrate for making electrical contact therebetween. Modern mass-manufacturing systems require flexible manufacturing stations that can pick and place different types of components with minimal supervision and with a high placement accuracy. Particularly with surface mount technology, the large volumes of production dictate that an automated or robotic approach be used to maintain competitiveness in the marketplace. The end effector must perform accurate and repeatable placement of components. It also must be flexible from placement operation to placement operation adjusting to different placing requirements.